JPH0757595A - Vacuum valve - Google Patents

Abstract

PURPOSE:To provide a vacuum valve having flat magnetic field distribution in the radial direction between electrodes and improved cutoff performance. CONSTITUTION:Slits are provided on the side face of a contactor holder 4 holding a contactor 10 to generate vertical magnetic field. A contactor holder 17 having a diameter smaller than that of the contactor holder 4 is connected to the back face of the contactor 10 at the center in the contactor holder 4, and slits are formed on its side face in the opposite direction to the slits of the contactor holder 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve, and more particularly to an electrode structure thereof.

[0002]

2. Description of the Related Art In recent years, a magnetic field parallel to an arc, that is, an axial magnetic field (hereinafter,
A vacuum valve having a longitudinal magnetic field electrode for applying a longitudinal magnetic field) is widely used. There are several types of vertical magnetic field electrodes, but here, the vertical magnetic field electrode shown in FIG. 6 will be described.

In the figure, two electrodes 1 and 2 having opposed end faces that come into contact with and separate from each other in a vacuum container (not shown) are arranged coaxially. These electrodes are provided with contact holders 3 and 4 each having a hollow cylindrical shape, and are connected to current-carrying shafts 5 and 6 at their bottoms. Further, contacts 9 and 10 are brazed to the end faces of the contact holders 3 and 4 and the central supports (reinforcing members) 7 and 8 to suppress the generation of eddy currents on the contacts 9 and 10. The slits are sufficiently formed in the radial direction. Counterbore portions 11 and 12 are provided on the back surfaces of the contacts 9 and 10 to center the contacts 9 and 10.

On the other hand, the contact holders 3 and 4 are contact holders 9 and 10, respectively.
Slits 13 and 14 tilted with respect to the rotation axis of the respective electrodes are provided, and these slits 13 and 14 run in the same direction in both electrodes 1 and 2. The support bodies (reinforcing members) 7 and 8 in the central portion are
Since it is made of a high resistance material such as SUS, most of the breaking current flows through the contact holders 3 and 4. Therefore, the current flows through the current-carrying paths formed between the individual slits 13 and 14 while rotating in the same direction in the opposing electrodes as indicated by the arrow in the figure. A longitudinal magnetic field is generated between the electrodes due to the circumferential component of the current flowing through the contact holders 3 and 4. At this time,
The magnetic field strength distribution generated at the center between the electrodes is approximately as shown in FIG.

[0005]

As a result of investigations on the magnetic field and the breaking performance, it has been found that there is a magnetic field strength with which the arc voltage becomes the lowest.
Regarding the magnetic field distribution, the flat characteristic in which the radial distribution of the magnetic field strength is shown in FIG. 5B has a better breaking performance than the characteristic in which the radial distribution shown in FIG. I know it's excellent.

By the way, in the conventional electrode structure, the radial distribution of the magnetic field strength is essentially a characteristic having an inclination with respect to the radial direction. Therefore, even if the electrode diameter is the same, the breaking performance becomes smaller than that of the electrode structure in which the radial magnetic field distribution is flat. For this reason, in order to make the radial distribution of the magnetic field strength flat, the slits in the radial direction are not sufficiently inserted in the contacts 9 and 10, and
It is also conceivable to generate an eddy current and use a magnetic field in the opposite direction generated by the eddy current to flatten the radial distribution of the magnetic field strength. However, since a phase shift occurs between the current and the generated magnetic field, an axial magnetic field is applied even at the current cutoff point, which adversely affects the insulation recovery characteristics after the current cutoff and deteriorates the cutoff performance. An object of the present invention is to provide a vacuum valve in which the magnetic field distribution in the radial direction is flattened to improve the breaking performance.

[0007]

In order to achieve the above object, the present invention has a pair of contacts that can be contacted and separated in a vacuum container, one of which is connected to a current-carrying shaft and the other of which holds the contacts. A vacuum valve having a slit for generating an axial magnetic field on the side surface of the first contact holder
A second contact holder is provided inside the contact holder with a slit opposite to the slit on the side surface, and the second contact holder is connected to the back surface of the contact. .

[0008]

In such a structure, the slits formed in the first contact holder and the second contact holder provided therein are made in opposite directions, and the magnetic fields generated by these contact holders are reversed. Since the directions of are opposed to each other, the magnetic field distribution in the radial direction between the electrodes can be flattened.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same components as those of the conventional one are denoted by the same reference numerals and the description thereof will be omitted. Here, only one of the electrodes will be described.

FIG. 1 is a front view of an electrode portion of a vacuum valve of the present invention, FIG. 2 is a plan view of FIG. 1, FIG. 3 is an AA sectional view of FIG. 2, and FIG. 4 is a BB sectional view of FIG. Is. In these figures, the contact 10 has a slit with a length sufficient to suppress the generation of eddy currents, and the contact 10 and the contact holder 4 correspond to the portions surrounded by each slit. Then contact
Brazed by 15.

Inside the contact holder 4, there are provided contact holders 17 and 18 which also serve as reinforcements, of which the contact holder 17 in the center is in the middle. The inner diameter is slightly larger than that of the contact holder 18. These contact holders 17 and 18 include contact holder 4
A slit is formed in a direction opposite to the direction of the slit 14 that is cut in. A plurality of contact holders 18 are evenly arranged in the circumferential direction. The contact holders 17 and 18 are brazed at the centering counterbore holes 19 and 20 provided in the contact 10 and the contact holder 4.

Next, the operation will be described. The contact holder 4 is provided with a slit 14 for generating a vertical magnetic field. Therefore, when the breaking current flows in the contact holder 4, the magnetic field distribution generated between the electrodes is similar to the magnetic field distribution formed in the central portion of the pair of one-turns, as shown in FIG.
It has the distribution shown in.

On the other hand, there is a contact holder 17 inside the center of the contact holder 4, and this contact holder 17 is opposite to the direction of the slit 14 cut in the contact holder 4. The slit is cut. In the present embodiment, the resistance value at both ends of the contact holder 17 is increased so that a current of about 10% of the total current flows through this portion, and in addition, the resistance value of SUS etc. Made of high resistance material. The above resistance value may be determined by changing the cross-sectional area of the cylindrical portion of the contact at the center.

Here, a part of the breaking current is caused by the contact holder 17
The magnetic field as shown in FIG. 5C is generated in the center between the electrodes by flowing to. Further, a plurality of contactor holders 18 provided between the contactor holders 17 and 4 are arranged in the circumferential direction, and this shape is almost the same as the contactor holder 17. In the present embodiment, the resistance value of the holder is adjusted so that about 20% of the total current flows into the holder 18. The distribution of the magnetic field generated between the electrodes due to the current flowing in these holders 18 becomes the distribution shown in FIG.

Therefore, the magnetic field distribution (c) formed by the contact holder 17 and the contact holder in the distribution of FIG.
When the magnetic field distributions (d) created by 18 are overlapped,
It is possible to obtain a characteristic such that the magnetic field distribution in the radial direction between the electrodes becomes flat as in (b).

The magnetic field generated by the contact holder 4, the center holder 17 and the intermediate holder 18 causes the contact 10 to have a sufficient slit for suppressing the eddy current, and therefore is the same as the current. The obtained magnetic field distribution b has no phase with respect to the current. Therefore, the residual magnetic field at the current interruption point, which has been a problem in the past, can be ignored.

By the way, it is basically sufficient to provide the above-mentioned contact holder 17 for flattening the radial magnetic field distribution between the electrodes, but in the present embodiment, the above-mentioned contact holder is provided. The reason for providing 18 is as follows.

That is, even if the magnetic field distribution in the radial direction is made flat as shown in FIG. 5B, the arc concentration occurs at a certain critical current value or more, and the energy due to the arc concentrates on a part of the electrode. Due to the stagnation, there is a possibility that the electrodes may be melted and the interruption may not be possible. For example, if the arc is concentrated in a portion C shown in FIG. 2 when the breaking current exceeds a certain critical current value, the current value flowing in the contact holder 18 directly below the region C is in a diffused state. It will be bigger than it was. Therefore, the magnetic field distribution created by the contact holder 18 becomes larger than the magnetic field strength of (d) as shown in (e) of FIG. Therefore, the total magnetic field strength applied to the concentrated arc column is smaller than that in other areas on the electrode surface. By the way, although the current flowing from the concentrated arc region C between the slits 14 of the contact holder 4 also increases, the action of the slit of the contact 10 and the connector 15 causes the magnetic field in the region where the magnetic field produced by this current is concentrated. It is designed to flow so as to strengthen the magnetic field in the area next to it so as not to strengthen it. That is, since the energy of the entire arc is reduced, the arc moves to a region where the magnetic field is strong, and it is possible to suppress the stagnation of the arc concentration. By providing the contact holder 18 in this manner, it is possible to prevent the possibility that the electrodes cannot be cut off at the critical current value that prevents melting of the electrodes, and further improve the reliability.

[0019]

As described above, according to the present invention, the first contactor holder for holding the contactor is provided with the slit for generating the axial magnetic field, and the second contactor is provided inside the holder. Since the contact holder has a slit formed in the opposite direction to connect to the back surface of the contact, it is possible to make the magnetic field distribution in the radial direction between the electrodes flat and improve the breaking performance. it can.

[Brief description of drawings]

FIG. 1 is a front view of an electrode portion of a vacuum valve showing an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view taken along line AA of FIG.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a diagram for explaining a radial magnetic field distribution between electrodes.

FIG. 6 is a front view of an electrode portion of a conventional vacuum valve.

[Explanation of symbols]

3, 4 ... Contact holder, 10 ... Contact, 14 ... Slit, 17
… Contact holder (center part), 18… contact holder (middle part).

Claims (2)

[Claims] 1. A magnetic field in the axial direction on a side surface of a first contact holder that has a pair of contacts that can be brought into and out of contact in a vacuum container, one of which is connected to a current-carrying shaft and the other of which holds the contact. In a vacuum valve provided with a slit for generating the above, a second contact holder having a slit opposite to the slit on a side surface is provided inside the first contact holder, and the second contact holder is provided. A vacuum valve in which a contact holder is connected to the back surface of the contact. 2. A third contact holder having a diameter smaller than that of the second contact holder is provided between the first contact holder and the second contact holder, and the third contact holder is provided. 7. A slit in the same direction as the slit of the second contact holder is formed on the side surface of the contact holder of, and the third contact holder is connected to the back surface of the contact. The vacuum valve according to 1.